Patent GB-577292-A (GB)
Title: Improvements relating to the alkylation of hydrocarbons
IPC: C07C2/86
Filed: 1943-12-16
Abstract: The alkylation of hydrocarbons with an alkylating agent consisting of an olefin, alcohol, ether or alkyl ester in the presence of a liquid alkylation catalyst of greater specific gravity is effected by maintaining a body of said catalyst of substantial height as the continuous phase and introducing a mixed feed of hydrocarbon and alkylating agent in liquid phase with the hydrocarbon in substantial molar excess through a dispersing orifice into the lower portion of the body of catalyst without sufficient agitation to produce an emulsion, the feed being thereby dispersed as drops which rise through the catalyst while alkylation is effected, the drops coalescing to form a superposed hydrocarbon layer which is withdrawn and alkylate recovered therefrom.  The liquid catalyst includes not only true liquids such as hydrofluoric acid but also liquids containing dissolved or suspended gases or solids such as hydrofluoric acid-boron fluoride and aluminium halide-hydrocarbon complex with free aluminium halide.  The dispersing orifice is generally about 1/32 -\ba1/2 in. diameter and the drops do not exceed about 1/4 in.  A separator or trap is provided adjacent the withdrawal point of the hydrocarbon layer, wherein any catalyst carried over separates and can be returned directly by gravity, wholly or in part, to the reactor with make-up catalyst.  The separator may also function as a reservoir for hydrocarbon when recycling thereof is employed.  A high recycle ratio of about 10-50 or more vols. per vol. of fresh feed is preferred.  The reactor may be a packed or unpacked tower with an orifice plate near the base, the space beneath this remaining filled with the mixed hydrocarbon feed.  One or more orifices or vertical nozzles are provided in the plate to produce the fine dispersion required, the feed rate generally being such that the interface level in the tower approaches its maximum height, but being below that at which the feed accumulates around the orifice with the breaking off of globs and a fall in the interface level.  With a single orifice, the height of the tower should be many times its diameter, for example 5-20 ft. or more by 1-12 ins. or more.  With a plurality of orifices, nozzles or other distributing devices, which may direct the spray in an inclined or horizontal direction over the cross-section of the tower, a relatively larger diameter may be used, for example 2-6 ft. or more. A plurality of towers may be connected in series.  Alkylation of iso or normal paraffins such as butanes and pentanes or mixtures thereof may be effected with olefins such as ethylene, propylene, butenes, pentenes, butene polymers and cracked gasoline fractions.  Aromatic and naphthene hydrocarbons may also be alkylated, for example benzene with ethylene or propylene.  Other alkylating agents specified are isopropyl alcohol and ether, tertiary and secondary butyl alcohols, alkyl halides, sulphates and phosphates.  Pressure is sufficient to maintain the liquid phase, and temperatures range generally from about -40 DEG  to 150 DEG  F.  The temperature of the feed and recycled hydrocarbons may be preconditioned by means of a chiller or heat exchanger.  Part of the separated hydrocarbon product is withdrawn, neutralized, stabilized by removal of unreacted gases which may be recycled, and fractionated to yield desired products such as an aviation fraction.  In examples: (1) isobutane is alkylated with a C4 cracked fraction using HF as catalyst in a steel tube 7 ft. x 1 in., water-cooled and connected by its overflow with an inclined separator of copper 7 ft. x 2 in.  The isobutane: olefin molar ratio is 5 : 1 and temperature 70 DEG  F.  The reactor may be packed with jack chain; (2) isobutane is alkylated with ethylene using aluminium chloride suspended in a complex thereof with kerosene, and hydrogen chloride as promoter, under the conditions set forth in Specification 574,678.  A packed steel tower 15 ft. x 1 in. with a 1/4 in. fuel orifice is used; (3) normal butane is alkylated p with ethylene or propylene using HF containing dissolved BF3 in a stainless steel tower with a 1/8 in. feed orifice.  The height of the catalyst is 108-109 ins. and normal butane saturated with BF3 is introduced with the hydrocarbon feed.